function [aero_up_pre,aero_down_pre,aero_up_con,aero_down_con,S_aero_up,S_aero_down]=interpolate_point(coef,aerobox,stru_quad_up)
aero_up_pre=[];
aero_down_pre=[];
aero_up_con=[];
aero_down_con=[];
S_aero_up=[];
S_aero_down=[];
for i=1:size(aerobox,1)
    if ismember(aerobox(i,1),stru_quad_up)
        aero_up_pre(end+1,1)=aerobox(i,1);
        aero_up_pre(end,2)=(aerobox(i,3)+aerobox(i,7)+aerobox(i,11)+aerobox(i,15))/4.0;
        aero_up_pre(end,3)=(aerobox(i,4)+aerobox(i,8)+aerobox(i,12)+aerobox(i,16))/4.0;
        aero_up_con(end+1,1)=aerobox(i,1);
        aero_up_con(end,2)=(aerobox(i,3)+aerobox(i,7)+aerobox(i,11)+aerobox(i,15))/4.0;
        aero_up_con(end,3)=(aerobox(i,4)+aerobox(i,8)+aerobox(i,12)+aerobox(i,16))/4.0;
        S_aero_up(end+1)=norm(cross(aerobox(i,11:13)-aerobox(i,3:5),aerobox(i,15:17)-aerobox(i,7:9)))/2;
    else
        aero_down_pre(end+1,1)=aerobox(i,1);
        aero_down_pre(end,2)=(aerobox(i,3)+aerobox(i,7)+aerobox(i,11)+aerobox(i,15))/4.0;
        aero_down_pre(end,3)=(aerobox(i,4)+aerobox(i,8)+aerobox(i,12)+aerobox(i,16))/4.0;
        aero_down_con(end+1,1)=aerobox(i,1);
        aero_down_con(end,2)=(aerobox(i,3)+aerobox(i,7)+aerobox(i,11)+aerobox(i,15))/4.0;
        aero_down_con(end,3)=(aerobox(i,4)+aerobox(i,8)+aerobox(i,12)+aerobox(i,16))/4.0;
        S_aero_down(end+1)=norm(cross(aerobox(i,11:13)-aerobox(i,3:5),aerobox(i,15:17)-aerobox(i,7:9)))/2;
    end
end
S_aero_up=1/coef^2*S_aero_up;
S_aero_down=1/coef^2*S_aero_down;
end